Here on Earth, Mars and most of others if not all terrestrial planets in the universe, iron is their most common metallic element because iron is in general the most common metal in the universe.
Here on Earth, a desert's sands are mostly 1 of these 3 colors:
Beige: By far the most common color in Earth's deserts and probably in the universe too. Almost all deserts are mostly some shade of beige, for example, the Sahara is mostly beige except for a few areas
Reddish orange: The best example would be Australia. Their deserts get so red that even martian soil falls short in comparison... Well in reality mars is mostly brown. You can even clearly see how Australia is way redder than any other landmass just by looking at it from space, so much redder in fact that it's often called "the red continent". The orangey sands are because australian soil contains some iron and in contact with the air (oxygen) it simply rusts.
Black: Black deserts are not very common and they are all quite small since they are just the product of old volcanic eruptions that left behind a lot of black basaltic rocks around them that eventually got wind-eroded into sand. An amazing example is Waw An Namus, it's big enough of a place that it can easily be seen high up from space as a black dot in the middle of the Sahara, you can easily find it just by view if you search it on google maps/earth.
Now, what about blue-green deserts? These would be the result of, instead of iron rich soil, copper rich soil. As iron, copper rusts in contact with oxygen but copper rust is not red as iron's is blue-green! Here on Earth it seems there's not enough copper for us to get these amazing looking hypothetical deserts... But hey, at least we got this! Yes that is not photoshopped, the surreal place is just a 100×50 meters area in the middle of the Philippines called "kaman utek" and yes, its soil looks blue because of copper oxide. As far as I know, this place is unique and there's nothing quite like it here on Earth, might be wrong tho.
I believe this is proof enough that if a planet's soil is abnormally copper rich and has some oxygen in its atmosphere, huge blue deserts are possible just like Mars is pretty much a single huge brownish-red desert because of iron oxide. But what I don't know is (and here comes the question). Is it even possible in the real universe for a planet to have that much copper? Even if we are talking about 1 in a billion. And if not, at least some decently sized patches of blue sand dunes?
Thanks in advance!